In basic terms, a motorwell throughhull is a drainage pipe for the motorwell. Many engines utilize water as a coolant, and the coolant system may leak. Additionally, being in a marine environment, it is obviously just difficult to maintain a dry compartment for an engine or motor that transmits power to an external propeller or screw. Typically, a motorwell throughhull is used in the engine mount area of an outboard engine, an area that is particularly accessible by and prone to water entering.
The motorwell is separated from the exterior of the boat by a hull or by a bulkhead partition. The motorwell throughhull drains water or small debris that is in the motorwell to an exterior of the boat. Most motorwell throughhulls for smaller pleasure craft are not equipped with pumps so that the motorwell throughhull relies on gravity to drain the water from the motorwell. Therefore, the motorwell throughhull is exposed above the water line, and aesthetics combined with function are important to many boating enthusiasts.
The current industry standard for a motorwell throughhull is a brass tube having flared ends and an open passage between the ends. The brass tube is inserted through the hull and at least one of the ends is then flared after the insertion in order to mount the device. Alternatively, one end may be provided with a nut to secure the hull between the nut and the opposite flared end.
There are several common problems with the brass tube design. As the passage therethrough is open, the tube is susceptible to clogging by debris. Brass may provide a desirable aesthetic, and is soft enough that it may be readily flared during installation. However, brass is expensive and easily discolors and tarnishes in the marine environment.
Another problem is that the brass tube is sized for a particular hull thickness. Accordingly, a parts supplier or retailer needs to stock a slew of the brass tube design motorwell throughhulls having different lengths. This can also lead to problems where a particular motorwell throughhull is not exactly sized to the hull thickness, and, thus, the motorwell throughhull does not exactly fit: water can penetrate the interior of the hull if the motorwell throughhull is too long, and an improperly fitting motorwell throughhull can be unattractive as well as an obstacle.
U.S. Pat. No. 6,736,081, to Green, et al., describes a variety of general throughhulls or bilge fixtures. In one form, a central portion is provided with a flared end and a threaded end, the threaded end receiving a nut thereon. As these designs are generally for bilge pumping or other outlets, they contemplate having a tube or pipe connected to an interior end. To facilitate such connection, a number of the designs utilize a barbed or pronged inner end extending beyond the threaded end portion that receives the nut. In any event, using such throughhulls in a motor well likely would result in the threaded end portion protruding from the hull or bulkhead in an unattractive manner, may be an obstacle for persons in the boat, and may extend to a point above the water line within the compartment to be drained.
In another known design, a motorwell throughhull is provided with a central portion and a pair of stainless steel end caps that are press-fit onto the ends of the central portion. Certainly stainless steel caps are likely to be found more attractive than discolored brass, and the pressfitting gives the motorwell throughhull a clean appearance. The central portion is formed of plastic and has no threads formed thereon, which allows an installer to selectively size the central portion with respect to the thickness of the hull. However, pressfitting is a process that is more difficult than the average person would find simple threading, and it is difficult to pressfit the caps so that they are flush with the hull.
Accordingly, there has been a need for an improved motorwell throughhull.